There was a post on msn.com recently naming the best burger joints in the US. I can't find the link to that post for the life of me, but I remeber that one of the places named was Dyer's in Memphis, TN. I found a review of their food here: http://www.roadfood.com/Reviews/Writ...251&RefID=1251
Notice what the review had to say about the restaurant's hygiene practices:
Ew. EwewewewewewewewewewewewewewewewEW!!!A round of raw ground beef is held on the cutting board under a spatula and the spatula is whacked a few times with a heavy hammer, flattening the meat into a semi-compressed patty at least four inches wide....[and] is submerged into a deep, black skillet full of bubbling-hot grease, grease that the management boasts has not been changed since Dyerís opened in 1912! [emphasis added] Itís the grease that gives a Dyerís burger a consummately juicy interior while it develops a crusty outside and a unique, shall we say, intriguing flavor.
Our waitress explained that the grease is carefully strained every night after closing hour (usually about 4am; this is Beale Street, after all); and besides, the really old grease is always burning off, so the supply that supposedly never changes is, in fact, always changing.
I would think it would be in the owner's best interests to keep the vintage of his oil a deep secret--part of the 'special recipe' as it were.